Method of carbonizing coal briquettes



March 6, 1934. E. B. A. zwoYER Er Al. l1,950,017

METHOD OF CARBONIZING COAL BRIQUETTES vFiled Aug. 11, 1931 2sheets-sheet 1 Q EL? N m S m N T. W

2 Sheets-Sheet 2 R0 TARY CARBBNIZER BRlquErTes l COOLER Filed Aug.

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CUAL HEATER /zze E. B. A. ZWOYER E1' AL METHOD oF CARBONIZING COALBRIQUETTES BRnQuErTEs wer COAL AND March 6, 1934.

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i M TW R T 0R. WE M B aan method of treatment which Patented Mar. 6,1934 T OFFICE METHOD F CRBONIZING iC'OAL VBRIQUE'IJTES Ellsworth B. A.ZwcyenPerth Amboy, and Albert L. Stillman, Plainfield, N. J., yassignorsto The' General Fuel Briquette Corporation, New York,

N. Y., a. corporation of New York Application August 11, 1931, SerialNo. 556,378

7 Claims.

r1`his invention relates to a method for producingsmokeless fuelbriquettes possessing sufficient rigidity of structure, not only duringthe several stages of treatment, but to withstand handling,

transportation and maintain their form after ignition and while beingconsumed.

The type of briquettes with which the process is more particularlyconcerned involves the use of finely ground anthracite and a binder ofCoal tar pitch or sulphite pitch and molasses. The method of mixingproportioning, handling and briquetting this type of material is wellknown, but the briquettes as delivered by the briquettng press do notpossess the necessary strength and rigidity for ordinary use nor arethey smokeless. I-Ieretofore efforts have been made to render-suchbriquettes smokeless by exposing them to elevated temperatures, but theuidity of the binders during the heat treatment, the movement of thebriquettes in their heat softened condition upon each other, and similarconditions interferred with the successful commercial use of suchprocess on any substantial scale. It is one of the objects of thepresent invention to supply a will be economical throughout and in whichthe briquettes will be subjected to a series of treatments eachappropriate for the then particular condition ofthe briquettes.

The invention is illustrated in thegdrawings in which Fig. 1 illustratesa longitudinal section through the apparatus and Fig.`2 is a plan Viewof the apparatus shown in Fig. 1.

The temperature gures applied to these lig- Aures of the drawings arerepresentative of conditions prevailing in one method of practicing theinvention. Fig. 3 is a diagrammatic elevational view looking at thebriquette conveyor from the left side of Figs. `1 and 2. Fig. 4 is asimilar View of a coal fines conveyor viewed from vthe right side ofFigs. 1 and 2, and Fig. 5 is a similar viewk illustrating the operationsof the coal fines conveyor 22 viewed from the right side of Figs. 1 and2.

In connection with these drawings vit-is' to be presupposed thatbriquettes composed of about i-94% anthracite particles and 640% binderconstituted of coal tar and'bunker C fuelv oil or other suitable bindingmaterial such for example as sulphite pitch and molasses and shaped andcompressed in a press such as that shown in United States lfratentNo.1,627,222, are being delivered withmachine like regularity to a dragchain conveyor l. The briquettes are con-- -veyed by this-conveyor fromthe press to-the'preheater chamber 2 and reach the preheaten'while stillretaining a vtenfiperature of approximately 150 remaining from the presstemperature. The bottom of the conveyor trough consists of a gateVextending over the entire'wdth of the chain grate 3 in the preheatingchamber 2. The design of the gate is such thatit may be adjusted to anyangle necessary to cause'the briquettes to be deposited upon the chaingrate 3 as a quiescent single layer in which the individual brquettesare substantially out of pressure Contact with one another.

The chain grate 3 is endless andY acts as a conveyor on which theuncarbonizedbriquettes are distributed in asingle layer so that each mayreceive like treatment. The use of a standard make of roller chain 4acting as a roller bearing, interposedbetween the chain grate and thesupporting track 5, represents a markedimprovement over other structuresheretofore suggested for performing analogous service. The speed-of thechain grate is such that each individual briquette will remain in thechamber 2 fora period ranging from 2 to 5 minutes depending upon theparticular Vkindof briquettes andthe variation of temperatureconditions. ,Y ,f

For the heat treatment of the briquettea; a Stoker fired furnace 6furnishes suiiicient heat of suicient uniformity for the entirecarbcnizing operation to which the briquettes are subjected in theirpassage through Vthe entire apparatus, shownin the drawings, fromthepoint ofintroduction to the point of their discharge.

The temperature ofthe incoming gases passing from the furnace 6 andpassing into Contact with `thesingle layer of briquettes, in thepreheater chamber 2, is approximately 2000 F.V This approximatetemperature is readily maintainable by the employment of a kthermostaticfurnace control (not shown). As the temperature of the briquettesis'about 150 F. it is apparent that, as they enter the preheater 2, theyWill-at once` be exposedto the greatest difference intemperature and thehighest temperature vof the entire process. The result of this treatmentis to quickly surface harden the briquettes uniformly over their entiresurface to the end that they maybe successfully passed through the nextsucceeding operation notwithstanding thattheinner portions of thebriquettes are still in a soft condition. This effect is mosteffectively accom-v plished by individualizing the brique'tte'sjon thechain grate for 'if they werein pressure contact' with one another orrested one upon the other .as theydoon the cross conveyor 1,"the heatwould time to absorb the necessary heat from the furnot envelop thebriquet-tes uniformly and they would be soft and misshapen at theirpoints of compressive contact.

The temperature of the briquettes leaving the preheater 2 isapproximately 950 F. while the temperature of the furnace gases leavingthe preheater 2 is about 1200 to 14=00 F. say 1300 F. for example, atthe inlet end of the rotary carbonizer 7. The rotary carbonizer '7 maybe a tube approximately four feet in diameter arranged to be slowlyrevolved by mechanism (not shown) at a rate of about 1/4 R. P. M. Inthis rotary drum 'l the briduettes are rolled on`each other that is,subjected in a mass to a slow tumbling action, being in this wayuniformly exposed to the high temperature furnace gases, until at thedischarge end of the rotary drum 7 the carbonizing gases areapproximately 800 F. while the temperature of the briquettes is aboutl700. The rotary drum l is inclined so that the rotation of the drumcauses the briquettes to travellengthwise thereof while being gently agitated together in a rotary motion and the inclination is such that thebriquettes are maintained in the drum for about 15 minutes, or sufcientnace gases.' The degree of inclination of the drum 7 can be varied tolengthenor shorten the time for the brquettes to pass through thecarbonizer drum 7 according to the particular nature and constitution ofthe briquettes. In any event care is taken at the elevated end of thedrum "I that a tight t is provided, with the end of the preheater 2, toprevent leakage of the furnace gases and the entry of oxidizing air andtemperature loss at this point. An inclined wall 8 provides a smooth,connecting guideway for the briquettes between the time they leave thechain grate 3 and their entry into `the drum 7.

If desired the preheater may be wider than shown in the drawing and aplurality of drums may be used.

The operative rotating speed of the drum 'lis made extremely low inorder to eliminate the abrasive action on the briquettes, otherwiseoccurring in this part ofthe apparatus. If in connection with theparticular type of briquettes, too much abrasion should manifest itself,the speed of rotation is reduced and the inclination increased.

After the briquettes have passed through the drum '7 they have beenalmost completely carbonized and therefore rendered smokeless and byreason of the antecedent series of steps their Vshape has beenvpreserved and their strength greatly increased. In order, however, tostore the briquettes safely it is important that their temperatureshould be reduced to approximately 150. F. throughout 100% of the entiremass. In other words'a vcooling system must be provided which willreliably reduce the temperature to the stated point. Without suchtemperature reduction at any point, the briquettes otherwise, whenstored, are likely to catch afire.

below the critical point, is manifestly undesirable for many reasons.Atmospheric or forced air cooling are expensive in operation anduncertain.

To meet 'the necessary conditions, the procedureV -now to be describedwas devised and found to into intimate uniform contact with coal fines,from their place of storage, on their way to the mixer Quenching withwater, lwhile very effective as a temperature reducer to from which thebriquetting press draws its supply. Such coal fines are naturally moistdepending somewhat upon humidity, precipitation, length of time ofstorage, etc. At any rate they can be depended upon to have a moisturecontent of at least 15%. These moist coal fines are fed into theconveyor 10 by the conveyor 9 from an outside sourceof supply. Theconveyor 10 passes below the discharge end of the carbonizing drum 'land there receives the hot briquettes as they are discharged from thedrum '7. The conveyor i0 is in the form of a gravity discharge bucketelevator, which retains the briquettes and the coal fines, which havebeen deposited upon the briduettes from the conveyor 9, until they reachthe chute aperture 11 where they are dumped indiscriminately into saidchute 1l' and thence into the ele vated end of the cooling unit 12. Thenature and action or" the conveyors 9 and 10 are of standard and wellknown type. One available varietyis illustrated in Fig. 3 where thechains 10a carry buckets 10b, which, moving over plate 10c, pick up thebriquettes and subsequently the coal nes deposited on said plate by ascraper conveyor 9. The buckets 10b, on passing over the roller 10d,deposit their contents on the plate 10e and also advance the mixedbriquettes and fines into the chute 11. In the cooler 12 the wet coaland hot briquettes are now caused to intermingle thoroughly with eachother by the rotary action of the cooler unit 12. Moisture `evaporatedfrom the coal nes, by the heat of the briquettes, being carried away bythe current of air passing counter current through the cooler 12 intothe stack housing 13.` The lower end-of the cooler 12 comprises aseparating chamber inthe form ofY a screen 14, through which the driedheated fines are discharged into the gravity discharge bucket elevator15, while the briquettes substantially free from' the screened fines,and now having a uniform temperature of approximately 130 F., slide overthe spout 16 into suitable vehicles or conveyors by which they arebrought to storage, or shipped.

The'iines discharged into the elevator 15 which, as illustrated in Fig.f1, operates like the conveyor 10, comprising chains 15a carryingbuckets 15b, plate 15c,`and plate 15e are discharged into the chute 17,which leads to the elevated end of a rotary conditioning unit 18,through which in the opposite direction pass the furnace gases, from thefurnace 6 after they have done their work in the preheater 2 and inthecarbonizer drum 7, and where they still have a temperature of about 800F. The coal rines entering unit 18, have a temperature of about .130 F.,will be raised to about 250 F. as they pass through unit 18, while theexhaust gases from the drum '7, entering unit 13 at about 800 F. aredischarged into the stack 19 at approximately 30D-400 F. Fans 20 and 21maintain the proper draft requirements at the two stacks of theapparatus.

The'binders used for briquettes have a melting coal fines with whichthey are to amalgamate thereby effecting considerable economy in theirpartY of the operation. The hot coal nes distransported by the bucketelevator 22 illustrated I J plate 22e, upper plate 22e, said plate 22ehaving its delivery point directly anterior to the mixer, or to a placeof storage in the vicinity of the mixer, so that they can be used beforethey have lost their heat. The feed of coal fines into the conveyor l0can be regulated in consonance with the amount required in the mixer tokeep the briquetting press supplied with mixed material at the rate atwhich the press delivers `briqluetted product to the conveyor 1. It"will be noted, that proceeding in this manner, there will be'ample moistcoal fines fed to the hot briquettes entering the cooler 12 to effectthe necessary cooling of the briquettes in that unit. When startingoperations after a shut down, or new installation, heat is started infurnace 6, coal fines are fed into the elevated end of unit 18 orconveyed thereif desired by elevators 9 and 10, unit 12 and elevator 15, the fines being in this way preheated for the mixing operation. Aftersuflicient amounts of hot fines have been mixed with the binder to startsupplying the press for continuous operation, the press begins its work,delivering its product to conveyor 1 and in a very short time the entireapparatus shown in the drawings will function automatically and normallyin the manner hereinabove described.

The process hereinabove described lends itself to the production ofsatisfactory briquettes in which the binders may be of various kindsincluding such as contain asphaltic oil or asphalt coal tar and bunker Cfuel oil or bunker C fuel oil alone. In fact so far as the use of abinder composed of bunker C fuel oil is concerned, the processhereinabove described is, so far as we are aware, the only known processby which satis- .factory briquettes can be produced when that type ofbinder is employed. The initial high temperature treatment seems tocause reactions which leave an effective condition of cohesion in thebriquettes even in those cases where asphaltic binders or similarbinders, which ordinarily possess only an inferior binding capacity, areused. Thus the new process opens up elds of use for binder materialswhich have not thus far been usable with satisfactory effect incommercial practice.

The process described herein is particularly advantageous when used inconnection with anthracite briquettes but may, of course, be employed inconnection with material equivalent to anthracite in its behaviour inrelation to and in response to the said process. When, therefore, in theclaims we refer to anthracite coal, it is to be understood that weinclude equivalent material.

We claim:

1. The method of making coal briquettes, which comprises distributingraw compressed briquettes, composed of inely ground anthracite coal anda binder, as a single layer within a heating cham- Zher and passing themthrough said heating chamber as a quiescent single layer inwhichtheindividual briouettes are substantially not in pressure contactwith one another, subjecting said briquettes forthwith upon their entryinto said chamber to high heat, maintaining said briquettes said highheat region for a sumcient time to surface harden said briquettes 'outnot long enough to result in combustion or to carbonize them throughout,then in a separate stage carbonizing lthe criquettes at a lowertemperature appropriate for thoroughlycarbonizing such briquettes andsimultaneously subjecting said briquettes in a briquet-tes roll uponeach other, and nnally cooling the thus hardened and carbonizedbriquettes.

2. In a method of making coal briquettes containing particles ofanthracite coal, the steps which comprise mixing the coal with a binder,molding carbonizable briquettes therefrom, subjecting such briquettes asa quiescent single layer in which the individual briquettes aresubstantially out of pressure contact with one another to a high heatfor a short period to surface-harden them without carbonizing `themthroughout, withdrawing the briquettes from the zone of high heat, andthereupon in a separate stage subjecting said briquettes in a mass to aslow tumbling action so that the briquettes roll upon each other l andduring said stage carbonizing the briquettes at a lower temperatureappropriate for thoroughly carbonizing such briquettes.

3. In the method of making coal briquettes containing particles ofanthracite coal, the steps which comprise mixing the coal with a binder,molding carbonizable lbriquettes therefrom, subjecting such briquettesas a quiescent single layer in which the individual briquettes aresubstantially out of pressure contact with one another, to a high heatfor a short period suilicient to merely surface-harden them, withdrawingthe briquettes from the influence of high heat, then carbonizing` thebriquettes throughout at a lower temperature appropriate for suchcarbonizing of said briquettes while gently agitating them together in arotary motion, and subjecting the thus carbonized briquettes to acooling medium consisting of coal iines until the temperature of thecarbonized briquettes is below approximately 150 F.

4. In the method of making coal briquettes containing particles ofanthracite coal, the steps which comprise mixing the coal with a binder,

molding carbonizable briquettes therefrom, subjecting such briquettes asa quiescent single layer in which the individual briquettes aresubstantially out of pressure contact with one another, to a high heatfor a short period sufficient to merely surface-harden them, withdrawingthe briquettes from the influence of high heat, then carbonizing thebriquettes throughout at a lower temperature appropriate for suchcarbonizing of l said briquettes while gently agitating them together ina rotary motion, bringing the thus carbonized briquettes into intimatecontact with a cooling medium consisting of coal fines, having atemperature materially below the temperature of the briquettes, movingthe briquettes `and coal fines together in contact with each other untilthe coal nes have materially reduced the temperature of the briquettes,and separating the coal rines and briquettes.

5. The method of making coal briquettes containing particles ofanthracite coal, which oomprises mixing the coal with a binder, moldingcarbonizable briquettes therefrom, arranging such briquettes in aheating space as a quiescent single layer in which the individualbriquettes are substantially out of pressure contact with one anotherbringing high temperature combustion gases into contact with thebriquettes, moving the briquettes to said carbonzing space into contactwith said briquettes to carbonize the same throughout While gentlyagitating them together in a rotary motion, bringing the thus carbonizedbriquettes into heat-exchange relation with coal nes, and separating thebriqnettes and coal fines.

6. In the method of making coal briquettes containing particles ofanthracite coal, the steps which comprise mixing the coal with a binder,molding carbonizable oriquettes therefrom, subjecting such briquettes asa quiescent single layer in which the individual briquettes aresubstantially out of pressure Contact with one another to a hightemperature for approximately from two to five minutes to merelysurface-harden them, withdrawing the briquettesl from the influence ofhigh heat, and subjecting` the briquettes while gently agitating themtogether in a rotary motion to lower temperature for approximatelyiiiteen minutes to carhonize them throughout.A

7. In a method of making coal briquettes containing particles ofanthracite coal, the steps which comprise mixing the coal with a binder,

molding carbonizable briquettes therefrom, subjecting such brquettes asa quiescent single layer in which the individual briquettes aresubstantially out of pressure contact with one another to a high heatfor a short period sufcient to merely surface-harden them, withdrawingthe briquettes from the influence of high beat, then subjecting thebriquettes While gently agitating them together in a rotary motion to alower temperature Vto carbonize the same throughout, bringing the thuscarhonized briquettes into intimate Contact with moist coal iines,having a temperature materially below the temperature of the briquettes,retaining the briquettes and coal nes'in contact With each other untilthe coalV ELLSWORTH B. A. ZWOYER.Y ALBERT L. s'rIIiLiviAN.V

